An enzyme is a catalyst for a chemical reaction which occurs in the body. The enzymes are produced in the body, much in the same way that the body builds proteins are built. Enzymes, for the most part, are very specific to the reaction. For example, sucrase is the enzyme which catalyzes the breakdown of sucrose. Lactase catalyzes the breakdown of lactose. For people who are lactose intolerant, they do not produce a sufficient amount of lactase for the body to break it down. Our bodies produce these enzymes as needed. If a person has a genetic defect in their DNA it may affect the section of DNA which is responsible for directing the formation of the enzyme, then the enzyme may not form and their body may not process that particular substance.

An enzyme is a kind of big, complicated protein molecule, made mainly of hydrogen and carbon atoms, but with some other atoms as well. Both prokaryote and eukaryote cells use enzymes, so the first enzymes probably evolved around four billion years ago, together with the first living things.

A enzyme is a biological catalyst that speeds up a reaction without being used up itself in the end.An enzyme is called a substrate and the substance in which it acts on is called the reactant and you will finally get the result which is called the PRODUCT..

Example of enzymes in our body-amylase(secreted by the mouth and pancreas)